We performed measurements of carrier-phase-based two-way satellite time and frequency transfer (TWST-FT) with an A/D sampler and conventional TWSTFT system. We found that an instability resulting from a local signal at the satellite transponder was negligible. The short-term stability of 4 × 10(-13) at 1 s was achieved in a short-baseline measurement. The results showed good agreement with the GPS carrier phase.

Advanced satellite-based frequency transfers by two-way carrier-phase (TWCP) and integer precise point positioning have been performed between the National Institute of Information and Communications Technology and Korea Research Institute of Standards and Science. We confirm that the disagreement between them is less than at an averaging time of several days. In addition, an overseas frequency ratio measurement of Sr and Yb optical lattice clocks was directly performed by TWCP. We achieved an uncertainty at the mid-10 level after a total measurement time of 12 h. The frequency ratio was consistent with the recently reported values within the uncertainty.

The National Institute of Information and Communications Technology (NICT) has developed and tested carrier-phase two-way satellite time and frequency transfer (TWSTFT) as a next-generation technique applicable to greater distances and resulting in higher precision. A method different from that used for code-based TWSTFT is required for carrier-phase TWSTFT. We propose a new method based on variations of carrier phases for the propagation of signals. Using the ETS-VIII satellite launched by the Japan Aerospace Exploration Agency (JAXA) and the Time Comparison Equipment (TCE) system developed by NICT, carrier-phase TWSTFT experiments were carried out between two ground-based hydrogen masers separated by a baseline of 110 km. Our tests showed that the frequency difference between two hydrogen masers can be measured for averaging times larger than 1000 s and the precision of carrier-phase TWSTFT is about 100 times better than that of code-based TWSTFT.

A single KDP (potassium dihydrogen phosphate) crystal was grown in a supersaturated solution containing a metallic ion (Al 3+ , Fe 3+, or Cr 3+ ). The growth rate, morphology, and distribution of the metallic ions into the KDP crystal were measured as the ionic concentration and supersaturation in the solution changed. It was found that in the KDP crystal, Al 3+ and Fe 3+ were greatly concentrated, but Cr 3+ was diluted. Complete expressions for the effect of metallic ions on all aspects of the growth of KDP crystal were suggested. The growth rates of (100) and (101) faces were well correlated by the empirical equation and resulted in good estimation of morphology. The distribution of metallic ions into KDP crystal was also correlated by the distribution model.

NICT has completed a set of major upgrades in its systems for the realization of Japan standard time. One of the most significant changes is the introduction of hydrogen masers as signal sources for UTC (NICT) instead of Cs atomic clocks. This greatly improves the short-term stability of UTC (NICT). Another major change is the introduction of a newly developed 24-channel dual-mixer-time-difference system (DMTD) as the main tool for measurements. The reliability of the system is also improved by enhanced redundancy and monitoring systems. The new JST system has been in regular operation since February 2006.